Examine source code of useduck.com

{
  "name": "useDuck",
  "short_name": "useDuck",
  "version": "0.0.3.4resigned1",
  "default_locale": "de",
  "description": "__MSG_Description__",
  "manifest_version": 2,
  "author": "Marco Molkenthin",
  "homepage_url": "https://useduck.com/",
  "icons": {
    "16": "icons/logo-16.png",
    "32": "icons/logo-32.png",
    "48": "icons/logo-48.png",
    "64": "icons/logo-64.png",
    "128": "icons/logo-128.png"
  },
  "permissions": [
    "storage",
    "webRequest",
    "tabs"
  ],
  "web_accessible_resources": [
    "icons/logo.png"
  ],
  "applications": {
    "gecko": {
      "id": "support@useduck.com",
      "strict_min_version": "45.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "res/jquery/jquery-3.3.1.min.js",
        "scripts/layer.js"
      ],
      "css": [
        "styles/layer.css"
      ]
    }
  ],
  "background": {
    "scripts": [
      "res/jquery/jquery-3.3.1.min.js",
      "scripts/main.js"
    ]
  },
  "browser_action": {
    "browser_style": false,
    "default_title": "useDuck",
    "default_icon": {
      "16": "icons/logo-16.png",
      "32": "icons/logo-32.png",
      "48": "icons/logo-48.png",
      "64": "icons/logo-64.png",
      "128": "icons/logo-128.png"
    }
  }
}